Mark_ZZ3

Well I can't seem to lick this darn oil leak.

It all seemed to start when I changed to Aluminum cylinder heads.

The oil leak appears to come from the back of the motor on the passenger side. To date, I have changed, fixed, replace (either because of the leak or just because)

- Intake gaskets (made sure to sillycone the back and let it setup too).
- valve cover gaskets, aluminum valve covers, and a thin film of sillycone at the back of the cylinder head)
- PCV - new valve, checked all hoses, etc.
- checked oil pressure sending unit adapter. It is dry.
- checked rear main, it is not it. Oil comes down around torque convertor cover.
- I did a compression test last year and it was balenced across cylinders. So blow by should not be a concern ... but how much does one need to force oil out? I have 3 summers and 1 winter worth of driving. I would guess 25,000 miles on a rebuilt motor.


It seems like the oil comes out the dist hole. Could this be it? I run a high volume pump and the pressure is 60psi+ when driving, maybe 30 psi at hot idle.

I also have moly rings. I know they took forever to seal, perhaps they are allowing too much blow by?

It almost seems like it leaks out between the head and block, but that is not possible judging from the oil flow passages.


Anyone have some ideas? I welcome any answer, odd, strange, what ever.

Many Thanks,
Mark.

GMTech

Yes! There is a round, paper, distributer gasket that keeps the shaft from leaking oil. You may need a new one, or you may have not gotten all the old gasket off before using the new one.

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Mark_ZZ3

I replaced the dist. gasket when I redid the intake gaskets. I used all Felpro gaskets (as per the edelbrock recommendations).

I suppose it could be loose. I will look into that and see.

Perhaps the sealing surfaces are not true and the gasket can't do anything.

I'll check that one.

Mark.

camaro1j

iTrader: (1)

eastwood sells a tool that finds leaks. It finds leaks by you poring some dye into your oil. Then you drive a little. After that you look for it with a uv light and it will glow. They make them for oil, trans,power steering,fuel,and coolant. That is if it is bothering you that much. It costs 90.00 for the kit. If you are interested the # is 1-800-345-1178. If you get it let us know how it works.

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406
accel supper ram
6000 rpm Hyd roller cam
afr heads
spohn torque arm and crossmember
t-56 trans, [wier racing bellhousing and hydrolic throwout bearing]
9" ME rearend 3.91 Gears

Mark_ZZ3

I had thought about doing that. It is just so tight to get behind the engine to see anything.

$90 is a bit steep. I was hoping on $10 for dye. I have access to a black light.

Mark.

Guest

Ask Guido, he has the same problem.

It may be that something isnt aligned properly. Maybe the distributor flange on the intake is too low and its not sealing against the gasket. Try 2 gaskets.

89gta383

iTrader: (5)

Damn, 90 bucks to find a leak?

Jack the car up and get under it, inside it, or anywhere else you can to see and feel the leak with your fingers. It may still be coming from your valve covers or the back of the intake. Put your fingers back there to find out.

Mark_ZZ3

89GTA ... I have crawled, dug, banged my head, etc. to find it.

I expect I am battling one or more leaks. Fix one, then the other leaks.

Of course I make the assumption that once I change a gasket, that should not be the leak. In the case of the dist., perhaps I need double gaskets.

I can feel the oil at the back of the engine, kinda on the overhang of the cylinder head. It feels like it is leaking at the back of the intake and then running down the cylinder head edge, and around the starter, down the the torque convertor cover.

I have just retorqued the intake bolts (I think GM must have used something to antiseeze yet keep the bolts from loosening when using aluminum heads and steel bolts)

I will check again for the valve cover.

My engine is always clean and the oil is too, so that makes it tough to find. I guess I need to drive down some dusty roads!

MArk.

Guest

My process:

Clean everything, make sure theres no oil or residue on anything.

Drive car, maybe 5-10 miles, park it, let it cool.

Use a piece of tissue paper, and start touching areas where you think the leak is until you find it. If it was leaking badly, start over and drive less or just let it run a little bit.

Mark_ZZ3

Well I have not tried that out. It should help narrow it down to an "area".

Heck my neighbours need something to talk about ..

"Dear, he out there again, now he is cleaning his motor with kleenax!"

:-)

Mark.

Lov2xlr8

i have two peices of information, one is if you used the rubber intake gaskets instead of just permatex, you are probally leaking form there, and the other is that my ***** itch, but that doesn help you much. anyway, retorugue the aluminum heads, make sure they dont misaleign with any passages and use lts of permatex when assembling gaskets.

Mark_ZZ3

Lov2xlr8,

I don't use the rubber gaskets on the end. It is sillycone, blue permatex as I recall. I make sure to put enough on there, and I did not drive the engine for a while after it was assembled. I also used a mirror to check and make sure it was sealed and no gaps.

I was almost temped to put a 1" wide bead of it on the back of the engine ... "There, that'll fix it!". Luckily that wore off.

Mark.

graebz28

iTrader: (5)

I had a question regarding using the sillycone stuff.

Shouldn't you let the bead cure, maybe overnight so that is does not just shintz out the back of the manifold because has not taken a shape and solidified.

If it cured more it would reamin thick and have some consistancy. The last time that I help someone do a manifold, he had to hurry up and get it done and did not let it cure at all. Needless to say it started to drip a bit.

PS
You ball itchin foookers are too funny! HAHAHAHA

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Michael Graeber

My Garage

1)83 Z-28 T-Top: Full cage, 9" w/ lad.bars, Midwest Engine Tech 406sbc,Strip Dominator, 1000-CFM Demon Carb, Phase VI Chevy Bowtie Heads 2.05/1.60, .630" Crower roller set-up, 1 3/4 coated Hookers 3" true dual exhaust th400, fuel cell & still not running

2)89 Formula WS-6 305 TPI Auto Daily Driver: minor motor mods, more suspension stuff. MODS

JoelOl75

You should let it 'skin over' but a full cure isn't a good idea. RTV expands as it dries anyway.

P J Moran

Man, I'm there with you. I'm having the EXACT same problem. I have aluminum heads, too, and the assembly was done less than a year ago. It just started a couple of weeks ago, though. I have crawled over, under, and around my engine and can't actually see where the oil is coming from. Between the A.I.R. pipes, harnesses, and heater hoses, there's no way to actually see the source of the leak. I used multiple lights and mirrors and still can't get to it.

So, I decided it was the intake manifold (in the corner where it meets the head). I thoroughly cleaned the back of the engine, including the bellhousing and starter with mineral spirits (there's absolutely no oil left on any surface). I bought new gaskets, etc. and began the teardown. After pulling the plenum, coil, EGR control (and its bracket), and the distributor, I saw an oil stain on top of the manifold around the distributor hole.

Thinking that might be the leak, I sprayed carb cleaner around there to clean it off. It ran off the back of the manifold. I crawled under the car to see where the cleaner went, and it dripped off exactly where the oil had been! I thought, "Eureka! That's it! It's just the distributor gasket!" So, I stopped there and replaced the distributor gasket and reassembled.

Feeling so proud, I took the car for a test drive. Bummer! The leak's still there I can reach around from the driver's side, behind the distributor, and actually feel all of the suspect spots with my right hand. Everything was dry - except for one spot. The oil's coming from the bottom right hand corner of the intake where it and the block and the head meet. I can't see it, but oil on my fingertip revealed it. Guess what I'll be doing this weekend...

I'm amazed at how much oil is coming out, though. Good luck with yours.

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'87 IROC 5.7l TPI - original owner!

Mark_ZZ3

Hey I think I found my leak, or at least one of them.

This time it was my valve covers. Although I still think there is some coming from the mystery spot at the back of the engine.

Anyways, the valve covers. My aluminum valve covers have a rail to hold the gasket from slipping out. this rail is about 2/16" thick. the gasket was only 3/16 thick. So guess what, the cover can move around a bit, and the metal rail bottomed out and thus the gasket did not compress. Well at least that is what it looks like.

So I bought felpro cork ones that are 7/32" thick. Now I can not bottom out and I made sure to position the valve covers so that they were centered.

Not sure what covers you have, but something to consider.

As an FYI, the valve cover leak left a small puddle. My mystery leak usually left a drop or two over the night.

Mark.

P J Moran

Follow up:

Two days of driving after the intake "re-do" (100 miles or so) - no signs of leakage. That must have been it. I'll post another follow up next week.

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'87 IROC 5.7l TPI - original owner!

P J Moran

Second follow-up:

Two weeks, now, and still looks pretty good. There is still a very small leak there, though. It's not dripping or running down - just a wet spot. It was really bad, before the re-do. There were oil spots on my rear bumper! It's in the very corner where the head and the block and the intake come together. I think the leak is actually between the head and the block, near the intake. When I reassembled, I semi-cleaned this seam on the inside and made an attempt to apply a bead of silicone along it with my finger. That seems to have helped. If I end up in there again for some reason, I will thoroughly clean this seam, full length, and be sure to get a good coat of silicone on the inside. For now, to keep the engine clean, I will keep a rag stuffed back there tight up against the leak (you can't see it) and change it out every couple of weeks or so.

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'87 IROC 5.7l TPI - original owner!

graebz28

iTrader: (5)

Is it possible to have oil leak from underneath the rotor assembly inside the distributor cap housing.

I just pulled my distributor and saw oil on the inside, under the cap. There are two screens that are at the base of the housing, and it looks like one of them has heavy oil residue on it.

The the question is whether the leak is coming from under and blowing up into the case or leaking from the top of the shaft and leaking down.

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Michael Graeber

My Garage

1)83 Z-28 T-Top: Full cage, 9" w/ lad.bars, Midwest Engine Tech 406sbc,Strip Dominator, 1000-CFM Demon Carb, Phase VI Chevy Bowtie Heads 2.05/1.60, .630" Crower roller set-up, 1 3/4 coated Hookers 3" true dual exhaust th400, fuel cell & still not running

2)89 Formula WS-6 305 TPI Auto Daily Driver: minor motor mods, more suspension stuff. MODS

"No one with a good car needs to be justified." JBMHR - Ministry

[This message has been edited by graebz28 (edited August 26, 2001).]

mckenzie

Hello, if you have access to a black light, you can get a bottle of oil dye tracer from your local gm dealership for appx $5. pour in the bottle and drive/idle for a little while. look for leak with a black light. best of luck, tom

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86 iroc 305tpi auto. mild cam

chiefz28

does your block have a place for machnical oil pressure gauge.It's right behind the intake near the distributor.If your using an electric oil pressure gauge then the machanical on top of the intake will have a plug in it.I know my plug came loose and it leaked real bad.something to check.

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iTrader: (1)

Just another 0.02cents-I was oh s*** with my new engine when I saw some oil that looked like it was coming from the head gasket; finally figured out that the oil dipstick tube was oozing where it goes in the block and it blew up and back. Ahhhh, just add an O-ring!



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